Engine inlet-exhaust bypass means for exhaust driven superchargers



Sept. 3, 1963 D. w. TRYHORN 3,102,381

' ENGINE INLET-EXHAUST BYPASS MEANS FOR EXHAUST DRIVEN SUPERCHARGERS 2Sheets-Sheet 1 Filed Aug. 4, 1961 2 Merering Device Exhausr VSupercharger Turbine Blower 5 Fig. 6.

6 Cooler 2 Mererfing Dawes) K 4 m 1 F 2 9 .mm 00 mm GD M I m F Se t. 3,1963 D. w. TR YHORN ,3

ENGINE INLET-EXHAUST BYPASS MEANS FOR EXHAUST DRIVEN SUPERCHARGERS FiledAug. 4, 1961 2 Sheets-Sheet 2 17 Merer'ing 25 Device 18 Turbochargel \T"q f;

Cooler 20 21 2'2 s1 3 Donald ,Wilfred Tryhorn,

'Claims priority, application Great Britain Aug. 11,

-normal. r

H engine which is tem, and which is pressure charged by by a turbinepressor is arranged tion engine as set a r 3,162,381 Patented Sept. 3,1963 United Smtes Patencce 3,102,381 ENGINE INLET-EXHAUST BYPASS MEANSFOR EXHAUST DRIVEN SUPERCHARGERS Chalfont St. assignor'to The BritishInternal Combustion Engine Research Association, Slough, England FiledAug. 4, 1961, Ser. No. 129,434

1960 Claims. (Cl. 60-13) :Thisinvention relates to internal combustionengines which are pressure charged by a compressor driven by 4 arturbineactuatedbythe exhaust gases from the engine, and its object is to widenthe range of conditions over i which turbocharging of engines gives thedesired results.

Many engines do not give the ideal or desired performance whenturbochargednfor example, engines having an. expansion type or constantpressure exhaust system, very high, speed engines, engines with numbersof cyllnders' which do not divide into groups satisfactorily to suit apulse type exhaust system, or with siarnesed ports, and those in whichthe combustion chamber does not lend itself to the modificationsrequired for large valve overlap, or which cannot withstand very highcylinderpressures. It is advantageous, mechanically, that theturbocharger should be free running and not coupled tothe engine, a butit is thisfreedom of the machine to chooseits own speed and cycle ofoperations, which makes its thermodynamic performance 1 it is impossibleto obtain a desired charging condition in 1 a particular enginearrangement, although the desired condition has been obtainedwith thesame typeof turbocharger in aditlerent engine 7 difficult to control. Insome cases arrangement. 1 The present. invention provides a degree "ofcontrol of :the turbocharger characteristics, which may be variable,

and which ensures that a given turbocharger will operate satisfactorily,over a wider range of conditions, than In accordance I freshchargegwhich may be air, is metered, for example,

-by being passed through a positivedispl-acemenrt compressing' andexpanding machine operating in parallel with the engine, so that apredetermined volume of air per engine cycle is taken from betweentheturbocharger compressor and the engine and is delivered into the exhaustmanifold or duct at a point ,between theengine exhaust valve and theturbine, the remainder of the fresh charge pass'ng to the engine in thenormal manner.

The invention 00115151311131! improved-method of pressurefcharging aninternal combustion engine provided a with an exhaust gas driventurbocharger comprising. bypassing a cycle from the inlet system to theexhaust system.

characterised in that some of the air from the said comto bypass 'theengine inlet manifold a'metering device tothe said turbine. furtherconsists in antinternal combusforth in the preceding paragraph in andpasses through The invention with the present invention a volume of themamfolding or duct inletsto receive the bypassed air;

i 1 air, a and a :pressure, and gives power to the engine when its inletPeter" England 5 pressure is higher than its outlet pressure.

t The invention still further consists in an internal com- =bustionengine as set fourth in .the preceding paragraph .in-which the meteringdevice-is a positive displacement compressing and expanding machine.

The accompanying drawings show, by way of example only, severalembodiments of the invention in which:

FIGURE 1 is a diagrammaticrepresentation of one mode oftcarrying theinvention into effect,

FIGURE 2-is asection through valvesof an engine showing a mode ofcoolingthe exhaust valve;

FIGURE 3 shows in elevationand part section an engine having an exhaustturbinetprovided with a separate -FIGU RE -4 showsin elevation anengine, having an alternative arrangement;

FIGURES shows in elevation a still further arrangement; and

FIGURE 6 is a fragmentary elevation similar to FIG- A URE d but with adifferent drive means for the metering device;

FIGURE 1 shows an internal combustion engine 1, a ,metering device 2comprisingan engine driven positive displacement machine and a turbine 3driving a comprese sor 4. Air from thetcompressor 4 is deliveredtto theduct junction 5 Where the flow is divided, a first portion pass- 1 ingto the; metering device 2 to form the metered bypassed secondpportionpassingto the engine 1. A .charge cooler 6 may be provided,which issmaller than pnormal because the total volume of air does not passthrough it. If the engine is of the spark ignition type a carburettor isfiitted in this position. The exhaust gases 1 from the engine pass alonga duct to junction 7 where they are mixed with the metered bypassed air,and then H pass torthe turbine 3; L

The position of unction 7 may vary with the particular application. Forexample, it may form a junction of the actuated by the exhaust gases ofthe engine ducts at any convenient position as indicated in FIGURE 1, orthe bypassed air may be used to form a series of ,jetsblow-ing over thebacks of the exhaust valve heads, as-Hshown in FIGURE- 2, therebyproviding additional valve cooling, While the-air gains heat beforepassing to the turbine. The bypassed air is brought to the cylinder head8 through duct 9 and enters the space 10 between the cylinder head 8,and the exhaust duct 11. Theair enters the duct: 11 through holesrl2,blows on the .1 head of the valve 13 and joins the steam of exhaustgases. I Inan alternative arrangement described in detail later thebypassed air may pass through a jacket surrounding the exhaust manifold,before mixing with the exhaust gases, so that the air gains heat, whileoperator comfort and safety are increased. i i

Ina further alterna 've, as s own in FIGURE 3,the metered bypassed air,maybe taken from the metering device 2 by way of the duct 14 to aseparate inlet 15 of the turbine nozzle ring, thereby-avoiding thedecrease in the amplitude of the exhaust pulse which would be caused itby theijunction 7 of FIGURE 1. In two stroke cycle engines, and whenthe; positive displacement machine is engineor separately driven, thisarrangement ensures that during starting of the engine.

of air trapped in thejcylinder,

all the air that of the speed of rotation of the machine.

- the other portion .tnetering device or machine 2; Air

7 by pulleys 27, 28, pulleys 27 and 28 and the metering device is in theposition shown the air thereby passed through the turbine nozzles startsfor combustion the turbine spinning and so provides air In the simplestcase the metering device or machine 2 may be free running, the inertiaof the parts of the machine ensuring an approximation to the desiredcharacteristics, but in most applications a machine driv'en by theengine is preferred.

. The machine or may be any thermodynamic machine which is capable of.expansion and compression, the most suitable being a positivedisplacement compressor or blower, for example of the Roots, lobe, orsliding vane type. Such a-metering' machine'or device has an importantfeature in this application, in that the volume of air passing throughit per cycle is determined by its capacity and speed of opera-.

tion, and thus the weight of air being'bypassed per cycle is notafunction of the pressure difference between inlet and exhaust, which inturn is a function of the characteristics of the turbocharger andengine. Consequently, the metering of the bypassed air has a controllingeifect upon the weight of air passing to the cylinder of the engine, andupon the output of the turbocharger. The Weight of air bypassed isapproximately proportional to theweight and therefore the ratio passesto the exhaust system does so through the cylinder during the periodforwhich the inlet and exhaust valves are open atjthe' same time. Thus theturbine inlet temperature is no longer a feature which limits enginespeed; W en the charging system is operatingfinefiiciently themetering'machine takes power-from when the system is operatingefficiently it gives power to the engine shaft. In any engine system inwhich during normal operation thediiference in pressure between inletand exhaust is small, so that little power can' be obtained from themetering machine, the latter may be a throttle, which preferably'shouldbe adjustable in accordance with the load and speed of the engine; I v iIn cases where it is advantageous to vary the volume of air that isbeing bypassed, other than by variations in the speed of the eng' andthe positive displacement machine, or by providing a machine in whichthe throughput is variable independently A machine of the latter type isdescribed in British patent specification No. 665,484. Independentvariation of the volume of 'air bypassed, gives an increased degree ofcontrol of. the air pressure available to the engine, independently ofthe normal characteristiesxof a turbocharged engine.

In' the arrangement shown in FIGURE 4 air enters the v the air cooler 20and then to the inlet of the air passes along duct 22 to the from [themetering the jacket 23 surrounding the exhaust manifold 24. The exhaustgases from the manifold 24 and the air .from the jacket: 23 enter theturbine of the turbocharger 16. through duct 25, and leave :the turbinethrough duct 26.

The metering device 2 may be driven 29 and 30aand belts belt 31 may bespeed type whereby the ratio of the drive between engine andmeteringdevice or machine may be varied. When ltO be driven independently of theengine, the independent driving means may be mounted for pulleys 27 or29 in FIGURE 4. Thearrangenient shown in FIGURE- is similar to 31 and32, and of the variable device for metering the bypassed air manifold 21'while' from the engine 1 A, In combination that shown in FIGURE 4except that no cooler is provided and all the air from the compressor ispassed into the inlet manifold 21. Duct 33 leads from the manifold 21 toa variable throttle device 34, acting as a metering device, and airpassing through this throttle device enters the jacket 23 surroundingthe exhaust m'auifiold 24', or it may enter the exhaust manifold when nojacket is provided. The variable throttle 34 is controlled by thecombined action of the rack control rod 35 of the fuel injection pump 36and the governor 37, through a suitable linkage 38. I

The metering machine or device 2 is small compared witi a normalpositive displacement pressure charger for a given engine, si-nce'itdeals with a portion only of the total air, and only a light drive isrequired because it operates over only the pressure differencebetweenthe inlet and exhaust manifolds. I

The'device of FIGUREG differs from the device of FIGURE 4 in using anelectric motor 39 in placeof the mechanical drive 27, 28 29', 30, 31 and32, the metering as of the device of FIGURE 4.

"air required to cool the exhaust gases does not pass through theengine, the period during which the inlet and and thatdetails forcarrying maybe varied without departthe invention claimed.

the invention into effect ing from the scope and Iclaim: 1. In aninternal combustion engine having inlet and exhaust i said inlet system,

' the pressures are reversed.

2. Apparatus as claimed in claim 1, in which the compressing andexpanding metering device is coupled to the engine by means of avariable speed device.

as claimed in claim 1, in which the compressing and expanding meteringdevice is of the type of the speed of rotation of the device.

with an internal in which the throughput of air is variableindependently -.having an inlet manifold and an exhaust manifold, a

ins

1 who dr ven by exhaust from said displacement, device being and saidintake manifold,

and said discharge side being connected to said exhaust turbine. v I

5. In a supercharged internal combustion engine hava connection betweensaid blower and said intake manifold, and an exhaust system comprising apassage in the engine adjacent an exhaust port, an exhaust an air intakesystem comprising a blower, air intake manifold,

manifold, a turbine, and a connection between said manifold and saidturbine, the novelty comprising a rotary compression device of the typethat will also operate as a motor, positively connected to rotate at afixed speed ratio with respect to said engine and having an inlet sideand an outlet side when operating as a ump, said inlet side beingconnected to said inlet system and said outlet being connected to saidoutlet system.

6. The internal combustion engine of claim 5, in which said outletconnected to said exhaust system discharges 10 2 400 068 air into saidexhaust system into said passage in the engine adjacent said exhaustport, whereby the portions of the engine surrounding said passage arecooled.

References Cited in the file of this patent UNITED STATES PATENTS2,065,106 @Symons Dec. 22, 1936 2,385,366 Lysholm Sept. 25, 1945 BirkigtMay 14, 1946

1. IN AN INTERNAL COMBUSTION ENGINE HAVING INLET AND EXHAUST SYSTEMS, ACOMPRESSOR FOR SUPPLYING AIR UNDER PRESSURE TO SAID INLET SYSTEM, ATURBINE ACTUATED BY THE EXHAUST GASES FROM SAID EXHAUST SYSTEM DRIVINGLYCONNECTED TO SAID COMPRESSOR, BYPASS MEANS CONNECTED TO SAID INLET ANDOUTLET SYSTEMS TO TRANSFER A METERED QUANTITY OF AIR PER ENGINE CYCLEDIRECTLY FROM SAID INLET SYSTEM TO SAID OUTLET SYSTEM, SAID BYPASS MEANSCOMPRISING A COMPRESSING AND EXPANDING METERING DEVICE COUPLED TO THEENGINE SO THAT IT TAKES POWER FROM THE ENGINE WHEN THE PRESSURE ISHIGHER IN SAID EXHAUST SYSTEM THAN IN SAID INLET SYSTEM, AND GIVES POWERTO THE ENGINE WHEN THE PRESSURE ARE REVERSED.